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February 28, 2019

The Unpopular Classic in the Laboratory: The Bubble Trouble. And What Can Be Done to Resolve It.
 
Unfortunately, bubble trouble and chipped areas in veneer ceramics appear far too often. The devil really is in the details. In other words, a few minor details need paying attention to during work in order to avoid frustration later on. 

The most common reasons for these vexing occurrences are often more obvious than you would think. For example, if a crown or bridge is veneered with ceramic after casting, the metal surface needs to be prepared accordingly. Failure to do this could lead to an imperfect result. In short, the bond between the metal framework and the veneer ceramic determines the later success or failure of the work. This also, of course, determines whether you will be dealing with a happy or dissatisfied patient later on. 

Porous oxide accumulations are a particularly well disguised source of error. They contain large volumes of air. The air expands during ceramic firing and results in the unpopular bubble trouble in the veneer ceramic. Another source of trouble is trapped residues of investment material. The residues are often difficult to spot with the naked eye alone. However, they will become more obvious later on as they permanently and negatively affect the entire bond.

Therefore, removal with the right rotary instruments is of enormous importance. This raises the next question: Which of the many dental rotary instruments is the right one? Certainly not diamond burs or brown or pink stones? These might pull out bonding particles, which are then worked into the metal surface. During subsequent firing in the furnace, these are combusted and degassed, to the detriment of the painstakingly applied ceramic. 

Frameworks should therefore only be worked on with special tungsten carbide cutters. 
Ideally always in one direction. If this is done in all directions, this can lead to overlapping and air pockets. Komet has developed the DF carbide cutters specifically for this application. The fine diamond toothing of the instruments creates perfect surface conditions and promotes controlled roughening. In addition, the pyramid-shaped, tapered cutting tips create a larger surface on the metal, which in turn has a positive effect on the metal-ceramic bond. To prevent cross-contamination between alloy-foreign metals, customizing your own set of dental rotary instruments is recommended. 

Compass for everyday laboratory routines: which TC cutters for which material?
TC-Cutter-Chart.jpg


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